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Synagro Proposed Sludge Drying Plant (Dormant)

Editor’s note: This issue is currently dormant. We will continue monitoring the situation and may take up the issue in the future.


ynagro and Waste Management Inc.’s Proposed Sludge Drying Plant at Grand Central Landfill

According to EPA: “’Sewage Sludge’ refers to the solids separated during the treatment of municipal wastewater. The definition includes domestic septage. “Biosolids” refers to treated sewage sludge that meets the EPA pollutant and pathogen requirements for land application and surface disposal. See EPA’s biosolids program at the national level for more general information and documents.”

Delaware Riverkeeper Network has been involved over recent years in addressing the contamination issues arising from the disposal of sewage sludge and the application of biosolids to land.

Currently, we are working with the local community to address a proposal in Northampton County in the headwater regions of Waltz Creek and Little Bushkill Creek, which are located in the Delaware River’s Special Protection Waters and are also designated as High Quality streams under PA Department of Environmental Protection’s (PADEP) special protection waters program. 

Biosolids Processing

Waste Management Inc. and Synagro Technologies, a biosolids processing company, want to build an enormous thermal drying facility to process sewage at the Grand Central Sanitary Landfill on the border of Pen Argyl and Plainfield Township, PA, near homes and businesses, children’s athletic fields, and the two high quality streams. Named the “Slate Belt Heat Recovery Center”, the plant would be located on a 12.1 acre parcel of the Green Knight Energy Center (an existing landfill gas energy facility) lot, at the location of a former rock quarry site at the Grand Central Landfill, which is owned and operated by Waste Management Inc. The plant would use heat from Green Knight which would run on a combination of landfill gas and piped-in natural gas. 

They would truck in up to 400 wet tons, up to 50 truck trips, every day of human sewage sludge from states throughout the region to produce dried sludge pellets, a biosolids product sold as fertilizer (sometimes labeled “organic” or “compost”) and heat pellets. 

The project is currently under review locally and by the state.  The Plainfield Township Planning Commission and Zoning Office is currently reviewing and evaluating the applications before the municipality.  Plainfield Township has had several public meetings on the applications, which have changed over the last 2 years.  Variances are needed from the municipality if the project is to progress. 

Applications for state permits have been filed with PADEP.  It seems that the Delaware River Basin Commission will not be required to docket the project because the applicants has changed their proposal from a stream discharge of effluent from the facility to trucking the wastewater back out of the site.  This move will allow the facility to avoid stream discharge permitting, and review by DRBC. To see the PADEP applications go here: (GeneralNPDES).

The Sludge from Sewage Treatment Plants 

Sludge from sewage treatment plants not only contains human pathogens, but can also contain industrial waste components and heavy metals, chemicals, radioactive materials, pesticides, pharmaceuticals, microplastics and perfluorinated compounds, to name a few typically found.  The process of drying sludge produces dust that, if not fully contained, can directly impact the health of local residents and workers.  There is a growing body of scientific evidence of the pollutants and dangerous properties of sewage sludge and biosolids.  Polluting air emissions, wastewater discharges, stormwater runoff, and spills and leaks are some of the pollution pathways examine din the various research papers available. View the DRN Fact Sheet to see a collection of relevant papers.

Residents of the area are opposed to the facility because of air and water pollution concerns, public health effects, safety issues and property value decline.  In addition to producing dangerous air emissions from the drying process that could escape the filtering system, the proposed plant would greatly increase truck traffic and bring other potential impacts such as noise, lights, odors, and the risk of environmental impacts related to toxic substances and hazardous materials contained in the sewage sludge and wastewater to be handled and stored at the site and the chemicals that will be used and stored at the facility. 

The Concern

Delaware Riverkeeper Network is very concerned about the potential for air and water pollution from the activities proposed, the potential for groundwater pollution from the routing of stormwater into the quarry pond, the impacts related to the gas-fired heat plant and potential public health effects.

Residents Elisa and Tom Carlo of Pen Argyl have been involved since December 2016 and organized a community group Sludge Free Slate Belt to oppose the facility.  Hundreds of residents from the region have come out to numerous Plainfield Township public meetings and to educational programs such as a rally and informational meeting in 2017 organized by Sludge Free Slate Belt and a protest at the recent “information meeting” held by Waste Management and Synagro on May 3 at Wenona Park in Pen Argyl.

Plainfield Township Planning Board continues to hold public meetings on Synagro’ s application. They held one May 31 and July 16; the public and DRN asked questions at both meetings. The public wants more time to ask questions about the project at a public meeting. The next meeting is expected to be in August.

Throughout 2017 and into 2018, DRN worked with residents of the region to oppose the project both before the Plainfield Twp. Planning Commission and (PADEP) for the numerous state permits that would be needed for the project. The public and DRN commented throughout the application, technical and administrative review processes for the state permits. DRN’s comments utilized expert analysis we commissioned and staff research that raised substantive environmental issues every step of the way. One permit that PADEP deemed complete and issued as a draft permit was the air quality management plan, which was completely inadequate and did not institute air quality measures that would prevent harmful air pollutants from being emitted from the facility, reaching residents in Penn Argyl, Plainfield Twp., and beyond. Technical defects in the discharge permits that were under consideration were similarly lacking in necessary measures that would prevent ground and surface water pollution. The pollution would directly impact the high quality streams connected to the proposed sludge plant site – Waltz Creek and Little Bushkill Creek. The old quarry lake on the site was proposed to double as a stormwater basin but would become a conduit for contaminated stormwater that would run off the active sludge plant facility into the pond, infiltrating pollutants into groundwater and expressing to the surface water, as well as deliver polluted runoff to both creeks through uncontrolled direct runoff. These issues were extensively explained in comments to the Township and PADEP through DRN’s participation in the public process. Residents packed meetings and hearings because of the outreach and education done by the local community, aided by DRN’s action alerts. The township planning board’s deep examination of the environmental impacts involved made for long but completely engaging public meetings for more than 2 years. Numerous experts testified before the Township Planning and Zoning Boards during their deliberations in an exemplary public process by the local governments, led by Plainfield Township.

Throughout 2018, there continued to be a major disagreement between the applicant and the Township on some basic zoning issues. One of those issues is the applicant’s (wrong) insistence that the former quarry pond, “Sediment Basin #2” is not a waterbody so is not subject to the Township’s zoning regulation setbacks. The lack of a buffer for this groundwater-connected pond, which is a waterbody under Pennsylvania’s Chapter 102 regulations, would expose the groundwater and the Little Bushkill Creek and Waltz Creek to pollution from the sludge facility.  Hundreds of tons of toxic sludge would be offloaded and the wastewater from the sludge loaded back into trucks every day. These High Quality streams are right up against the site. See DRN’s letter and a report by Meliora on the classification of the quarry pond, sediment basin #2, as a waterbody and the danger of groundwater pollution and degradation of the streams. There are private wells, homes, a ball field, the community’s recreational trail, and the Town of Pen Argyl within a few hundred to 1000 feet of the site. See the cover letter and report submitted by DRN to Plainfield Township. Also see the cover letter submitted by DRN to PADEP with Meliora’s report on these issues.


After 3 years of struggle by the community against the proposal to build the sludge plant, in September 2019 the Plainfield Twp. Planning Commission voted not to recommend approval of the project. After some back and forth with the company, Synagro withdrew its application before the Township Committee could vote on it, and it was decided that the company could consider resubmitting a different application. However, in February 2020 a final decision was made by Synagro to abandon the project completely. As reported on February 3 in the news: “The developer of a proposed $26 million sludge treatment plant in the Slate Belt has decided to halt the project, ending a three-year controversy that divided some community leaders and many residents. Synagro Technologies Inc. notified Plainfield Township via a letter dated Friday that both the Baltimore company and Waste Management Inc. would quit the proposed Slate Belt Heat Recovery Center on Waste Management’s Grand Central landfill off Route 512.” ( ) This was followed by Synagro withdrawal al applications for the project that were pending before PADEP.

Visit the local organization working to oppose this plant: Sludge Free Slate Belt